(a) Field of the Invention
The present invention relates to a hollow metallic golf club head of the so-called "wood" head type.
(b) Description of the Prior Art
Golf club wood heads having a hollow metallic head body as disclosed for example in Japanese Unexamined Patent Publication No. 63-154186 are known, and are referred to as "metal woods". With the head disclosed in this publication, the head body is constructed by welding together two or three forged shell members. The divisions may be for example into three sections, namely a face, sole, toe, and heel section, a back section, and a top section, or into two sections, namely a front section and rear section formed by a dividing line between sole, toe, heel, and top portions. A shaft connection pipe for connecting a separate shaft to the shell member is fixed to the shell member by welding. In fixing the shaft connection pipe, the lower end is inserted to abut against the sole of the shell member.
Since this construction of the head involves connecting together two or three shell members as well as the shaft connection pipe, the large number of components means that the number of operations such as welding required in the manufacturing process becomes large so that costs are increased. Moreover, since the shaft connection pipe is a separate body, the strength of the shaft connection can also be a problem. Furthermore, the shaft connection pipe which protrudes in an upward direction from the top of the head has its lower end extending as far as the sole. Hence the weight of the front side of the head is increased by the shaft connection pipe. This increase in weight of the front side of the head, reduces the "sweet area". Here "sweet area" refers to a region on the face where a ball that is struck by this region flies stably and directly ahead. The "sweet area" can be increased by moving the overall center of gravity of the head further rearward (lowering the center of gravity).
With Japanese Utility Model Unexamined Publication No. 58-185252, although an iron club head is disclosed and not a wood club head, there is disclosed a container-shaped balance weight having an open front face connected to a rear face of a substantially planar face member which is formed integrally with a shaft connecting portion. The connection face of the face member and the balance weight is a planar face. With a construction such as that of this disclosure, the head is formed as two members, so that the number of members is reduced. However, since the positional relationship between the face and shaft for the iron club head differs from that for the wood club head, the construction disclosed in this publication cannot be applied as is to the wood club head.
With the conventional hollow metallic golf club wood head as described beforehand, the head body construction involves welding together the two or three shell members and the separate shaft connection pipe. Due to the large number of members, the number of operations in the manufacturing process becomes large, so that costs are increased. Moreover there can be problems due to the strength of the shaft connection being weak. Furthermore, since the lower end of the shaft connecting pipe extends as far as the sole, the weight of the front side of the head is increased, thus reducing the "sweet area".